This invention relates to a novel ester derivative useful as a component of liquid crystal compositions and a liquid crystal composition containing the same.
Display elements utilizing the optical anisotropy and dielectric anisotropy of liquid crystal substances have come to be broadly used. Depending on the kinds of liquid crystal display elements, physical properties required for liquid crystal substances used therein vary. For example, a positive dielectric anisotropy is required in some case or a negative dielectric anisotropy is required in another case. Further, liquid crystal substances are required to be stable to heat, air, light, moisture, etc. and also to exhibit liquid crystal phases in a temperature range as broad as possible. No single compound meeting such requirements has yet been found; hence liquid crystal compositions consisting of several kinds of liquid crystal compounds and if necessary, non-liquid crystal compounds have been practically used.
For display elements of twist-nematic mode which have currently been most often used, there have been desired liquid crystal substances having a positive large dielectric anisotropy value (hereinafter abbreviated to .DELTA..epsilon.) for reducing the threshold value of their driving voltage and also a small optical anisotropy value (hereinafter abbreviated to .DELTA.n) for reducing the visual angle-dependency of display elements.
A first object of the present invention is to provide a substance affording a positive large .DELTA..epsilon. of liquid crystal compositions and also reducing the .DELTA.n thereof when the substance is contained therein.
A second object of the present invention is to provide a liquid crystal composition containing such a substance.